Abstract

Background

Anterior mediastinal masses are a rare but well documented finding in Graves disease.
The vast majority of these lesions represents benign thymic hypertrophy and regress
after treatment of the hyperthyroidism. A small percentage of these cases however
represent neoplastic/malignant diseases which require further treatment.

Cases

12 year old boy with one year history of refractory Graves disease was found to have
an anterior mediastinal mass and underwent curative thyroidectomy for sustained hyperthyroidism.
Cervical lymphadenopathy was detected during the procedure and biopsy was obtained.
A 23 year old woman who presented with a one month history of hyperthyroid symptoms,
was diagnosed with Graves disease and also was found to have an anterior mediastinal
mass on imaging. Biopsy of the anterior mediastinal mass was obtained and subsequently
the patient underwent robotic thymectomy. Histologic examination and immunophenotyping
of the cervical lymph node in a 12 year old boy revealed neoplastic proliferation
of T lymphoblasts diagnostic of T lymphoblastic leukemia/lymphoma. Examination of
the anterior mediastinal mass biopsy in the 23 year old woman revealed type B1 thymoma
which was confirmed after examination of the subsequent robotic thymectomy specimen.

Conclusion

This is the first reported case of T cell lymphoblastic lymphoma and the third reported
case of thymoma associated with sustained hyperthyroidism due to Graves disease. These
cases indicate that an anterior mediastinal mass in a patient with active Graves disease
may be due to a neoplastic cause, which may require definitive treatment. Caution
should be exercised when dismissing a mediastinal mass as benign thymic hyperplasia
in patients with active Graves disease.